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1.
嵌入式USB主机系统的研究与设计   总被引:19,自引:0,他引:19  
介绍了USB主机的核心机制及设计方法。系统创新性的拓展了USB体系的结构,抛开了PC,把USB主机引入到嵌入式系统中,从硬件到软件,完全自主设计。整个系统没有依托任何嵌入式操作系统,因而具有普通意义。  相似文献   

2.
尽管USB设备的推出已经有些时日,而且现在的软硬件对USB设备的支持也比较好,但是还是经常会出现无法使用USB设备的现象。下面就针对一些典型的USB“病症”来谈谈常见USB设备故障的排除方法。 1.USB设备接到USB口后,系统没有反应,并没有发现什么新的设备? 对于这种情况,使用者应该先参照《USB设备安装指南》一文中“主板USB控制器的安装”部分的内容,仔细地看一下系统是否已经成功地安装了USB,具体从控制面板的“系统属性”中查看,如果没有,则可以参照上文中的内容进行相应的设置和安装工作。另外,对于带电源开关的USB设备  相似文献   

3.
本文介绍了以ARM为核G微处理器的嵌入式系统的设计方法,以及USB主机控制芯片在ARM系统中的扩展方案.在此硬件平台的基础上,对ucLinux操作系统的移植和应用进行说明,并探讨了USB主机控制芯片驱动程序的设计。  相似文献   

4.
对RS232转USB接口的通信方法研究设计   总被引:1,自引:0,他引:1  
USB通用串行总线是计算机外设接口的发展趋势,已经取代Pc机上的RS232协议串口,因此很多传统的RS232接口设备都将面临一个向USB接口转换的问题。本文以IC卡门禁考勤系统为例,提出一种方案,使传统的RS232接口转化为USB接口后直接通过USB总线接入PC,同时使IC卡门禁考勤设备增加了USB总线具有的热插拔、自动配置和智能电源管理等功能;着重剖析USB通信内核,探讨系统软硬件设计方案。  相似文献   

5.
王立萍 《福建电脑》2007,(7):41-41,21
USB是通用串行总线接口,能够实现主机和多台外设之间简单、快速、可靠的连接和通信,已成为计算机的必备接口。本文主要分析了USB总线的功能特点、USB系统的软硬件结构,以及简要说明了USB接口的实际应用和USB的新发展。  相似文献   

6.
朱晓锦  庞海珑  王健  邵勇 《计算机工程》2007,33(21):240-242
基于LPC2292(ARM7)为CPU、Nucleus PLUS为实时操作系统的测控系统平台,分析了以ISP1161A1 USB主机控制芯片构建USB主机模块的设计与实现方法,包括USB主机功能模块设计方案、嵌入式USB主机的硬件设计思路、嵌入式USB主机驱动程序的设计方法以及设计方案的实现方式和过程。针对主机驱动程序的主要相关功能、面向通用USB设备驱动程序接口和主机控制器驱动程序的下层数据管理等关键问题,给出了解决方案和实现方法,提供了关键数据结构和简明注释。  相似文献   

7.
USB总线(通用串行总线)快速、可靠、便捷、易用,是一种理想的数据传输方法、介绍了一种在CPCI总线系统中利用软硬件相结合的方式采集并通过USB实时传输数据的方法,从采集系统的工作原理和硬件、软件的实现方法等方面对采集系统的设计进行了说明、,着重介绍了USB设备及主机软件的设计方法。  相似文献   

8.
日前,我接到一朋友的求助,说他昨天新购买的爱国者USB可移动硬盘拿回家不能使用。于是,我便到他那里查了个究竟。打开计算机,运行软盘上的安装程序,依照安装向导的提示,一路点击“Next”按钮,完成后按提示重新启动计算机。启动成功后,将USB连线插到主机的USB接口上,双击“我的电脑”,发现系统中并没有预想的“可移动磁盘”图标。USB可移动硬盘驱动程序的安装非常简单,应该没有问题。仔细检查连接线,发现一切正常,重新换一USB接口,按“F5”键刷新系统,故障依旧。仔细回想重新启动计算机后,将USB连线插到主机的USB…  相似文献   

9.
USB是universal Serial Bus的简称。它是一种可以同时处理计算机与具有USB接口的多种外设之间通信的电缆总线,USB已成为目前PC标准的通用串行总线。一个基于计算机的USB系统可以在系统层次上被分为三个部分:即USB宿主(host)、USB设备(device)、USB连接(主要于USB2.0中涉及)。本文将分别对其进行叙述。  相似文献   

10.
Linux下MPC8272的USB主控制器驱动设计与实现   总被引:1,自引:1,他引:0  
从介绍USB协议标准以及USB主机端的系统结构入手,分析了在Linux操作系统下,USB设备主控制器和USB设备的驱动结构,并介绍了Motorola MPC8272处理器中USB主控制器功能及其特点,以此为基础设计和实现了USB主控制器驱动的功能模块,并在Linux操作系统下进行驱动开发以及进行测试验证.给出了一种在嵌入式系统中USB主机控制器驱动的实现方案,为同类的嵌入式USB主机控制器开发提供了借鉴.  相似文献   

11.
Land use changes have a pronounced impact on hydrology. Vice versa, hydrologic changes affect land use patterns. The objective of this study is to test whether hydrologic variables can explain land use change. We employ a set of spatially distributed hydrologic variables and compare it against a set of commonly used explanatory variables for land use change. The explanatory power of these variables is assessed by using a logistic regression approach to model the spatial distribution of land use changes in a meso-scale Indian catchment. When hydrologic variables are additionally included, the accuracies of the logistic regression models improve, which is indicated by a change in the relative operating characteristic statistic (ROC) by up to 11%. This is mostly due to the complementarity of the two datasets that is reflected in the use of 44% commonly used variables and 56% hydrologic variables in the best models for land use change.  相似文献   

12.
As office workers’ use of social networking sites (SNSs) has increased, so has research interest in the effect of SNS use on job performance. The present study employs data collected from South Korean office workers to examine how the use of the SNS Facebook affects job performance and to investigate the moderating effects of task characteristics (task equivocality and task interdependence). The results show that Facebook use for work has a positive effect on job performance, although the time spent on Facebook use does not have a significant effect on job performance. Moreover, task interdependence is associated with a decrease in the effect of Facebook use for work on job performance. In other words, task interdependence has a negative moderating effect on the impact of Facebook use for work on job performance. The reason is that Facebook is particularly advantageous for enhancing performance in tasks where the level of interdependence is low because it is a medium with relatively low synchrony and is unsuitable for one-to-one relationship building. This study has implications for companies that are concerned about formulating policies related to employees’ use of SNSs.  相似文献   

13.
This research examines the relationship between the predictors of use and the different conceptualizations of system use in a hedonic volitional setting (Facebook). Using the unified theory of acceptance and use of technology (UTAUT) model, an investigation into the three aspects of system use: the user, system and task were carried out. Results from a cross-sectional survey of 449 students show that behavioral intention has a significant influence on all aspects and dimensions of system use including cognitive absorption and deep structure use. Performance expectancy, effort expectancy and social influence are significantly related to system use. From the component model, performance expectancy is only significant with deep structure use. Hedonic performance expectancy is found to be significantly related to cognitive absorption. Results also demonstrate that predictors of usage have a significant relationship with the user aspect of system use. The variance explained in usage conceptualized as the user/task aspects is much higher than that of the system/task aspects or one-dimensional measures. Overall, conceptualizing system use using the user/task aspects offers greater explanatory power in Facebook use.  相似文献   

14.
软件开发中的用例分析技术   总被引:6,自引:1,他引:6  
叶斌 《微机发展》2004,14(9):118-121
用例技术是通过用例、参与者与用例以及用例之间的关系来描绘系统外在需求的一种方法。作为UML(统一建模语言)的一种重要表示法,用例分析方法在软件开发过程中占据着重要的地位。正确使用用例分析方法有助于项目的需求分析、体系结构设计、进度安排、测试和验证。文中简要介绍了增量/迭代式软件过程,通过实例探讨了软件开发中如何使用用例分析技术,包括项目风险分析、确定系统边界、细化事件流、图形化用例以及用例归档技术,从而为获取用例模型提供了有效的方法和途径。  相似文献   

15.
基于用例的需求建模方法   总被引:3,自引:3,他引:3  
张秋余  杨玥  王雪  王鹏  贾志龙 《计算机工程与设计》2006,27(19):3539-3540,3548
传统的软件需求规约是采用功能分解的方式来描述系统功能,而采用用例的方法进行需求获取和建模,是以用户为中心的建模方法.用例模型是由用例图和用例规约所组成的.用例图用来规定系统的行为,用例规约是用文档的形式对每个用例进行描述的.通过对银行系统进行基于用例的需求分析和建模,可以了解用例模型的益处.  相似文献   

16.
Many spatially explicit land use models include the neighbourhood effect as a driver of land use changes. The neighbourhood effect includes the inertia of land uses over time, the conversion from one land use to another, and the attraction or repulsion of surrounding land uses. The neighbourhood effect is expressed in the neighbourhood rules, but calibration of the neighbourhood rules is not straightforward. This paper aims to characterise the neighbourhood effect of observed land use changes and use this information to improve the calibration of land use models. We measured the over- and underrepresentation of land uses in the neighbourhood of observed land use changes using a modified version of the enrichment factor. Enrichment factors of observed land use changes in Germany between 1990 and 2000 indicate that the neighbourhood effect exists. This suggests that it is appropriate to use neighbourhood rules to simulate urban land use changes. Observed enrichment factors were used to calibrate a land use model for Germany from 1990 to 2000 and the obtained neighbourhood rules were validated independently from 2000 to 2006. The results show that both the allocation accuracy and the pattern accuracy of the land use model improved for the calibration period, as well as for the independent validation period. This indicates that enrichment factors can be used to improve the calibration of the neighbourhood rules in land use models.  相似文献   

17.
This paper begins by reviewing the application of use cases in the analysis and design phases of software development. At present, a use case derived in analysis is generally mapped into design through the synthesis of object behaviour for all scenarios associated with the use case. Hence the use case level of abstraction is not directly used in this process and a semantic gap exists between analysis and design. With informal textually based use case definitions this is to be expected, however, if the use cases themselves are given a more concrete structure, for example in the form of a statechart, then their direct use becomes more feasible.In this paper we therefore investigate the application of use case structures in the initial design phases of software development. A novel approach is proposed that applies a state based use case model directly to each object in the design architecture. This requires the derivation of a set of repeatable refinement procedures, which remove redundancy and allow the assignment of behaviour to objects with respect to their responsibilities. It is then shown how such procedures may be used in design, filling the semantic gap between analysis and design. By applying the procedures to a case study we identify and evaluate the characteristics of the mapping from use case model to object behaviour and review our approach with respect to other methods. It is concluded that state based use case structures not only represent a succinct analysis format, but may also be used to map analysis models directly into the design process.  相似文献   

18.
云计算技术在教育领域中的运用,能够使科技教育更加快速有效的进行。但是云计算技术是一项新型的计算模型,它在计算方面运用了多方面互联网计算审核技术,将这样强大的技术进行教育运用,存在着一定的创新性和技术性,在创新运用和灵活运用的同时,我们更要注意的它的各项细节特征的变化。  相似文献   

19.
In a use case driven development process, a use case model is utilized by a development team to construct an object-oriented software system. The large degree of informality in use case models, coupled with the fact that use case models directly affect the quality of all aspects of the development process, is a very dangerous combination. Naturally, informal use case models are prone to contain problems, which lead to the injection of defects at a very early stage in the development cycle. In this paper, we propose a structure that will aid the detection and elimination of potential defects caused by inconsistencies present in use case models. The structure contains a small set of formal constructs that will allow use case models to be machine readable while retaining their readability by retaining a large degree of unstructured natural language. In this paper we also propose a process which utilizes the structured use cases to systematically generate their corresponding use case diagrams and vice versa. Finally a tool provides support for the new structure and the new process. To demonstrate the feasibility of this approach, a simple study is conducted using a mock online hockey store system.  相似文献   

20.
用例作为展现程序系统级行为的有效手段,可以辅助理解程序的功能特征。针对面向对象系统提出了一种基予关注点的用例模型逆向生成方法。该方法分析目标系统运行时的动态信息,把其中方法调用序列的起始方法看作基本用例,使用一定的规则识别出基本用例间的关系来合并生成用例,依据从用户的关注点中获取到的有用信息,对生成用例进行改进,从而实现了用例模型的逆向生成。通过实验分析,表明该方法在恢复用例模型并提高其准确性方面是有效的。  相似文献   

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